Communications infrastructure equipment employs a variety of power system components. Power factor corrected (PFC) AC/DC power supplies with load sharing and redundancy (N+1) at the front-end feed dense, high efficiency DC/DC modules and point-of-load converters on the back-end. These systems ensure a stable and uninterrupted power supply, which is critical for the operation of telecommunication networks. 5 Survey Diagram, Block Diagram and Functioning Principle of the d. 5 kVA 266Let's start with brief description of seven most known and most used communication medias used in power system communications (in terms of protection and automation): Economical, suitable for station to station communication. Equipment installed in utility owned area. Limited distance of coverage. To carry out each of the communication protocols, the Open Systems Interconnection (OSI) model is presented, the main objective is to have a structural guideline to exchange information between computer systems, networks and terminals [ 2]. Divided into 7 layers, the OSI system facilitates the.